Light-curable compounds, such as adhesives and bonding or filling compounds, are widely used to attach objects to surfaces or to fill gaps or other openings. Such compounds have a particular use in dentistry, such as to bond dental work or fill gaps, such as a cavity, in a tooth. Such curable compounds are generally available in a semi-solid state, and are manipulated and positioned on a work surface or in the gap as desired, and hardened or cured into a more solid state for permanency. Curing or hardening is generally a chemical polymerization process that is promoted and driven by various curing conditions and factors. For example, a semi-solid compound or component thereof, may be cured by exposure to air or to energy, such as heat or light energy.
Today, many adhesive and filling compounds are cured by exposure to light energy, particularly visible light energy. The light curing process involves directing a beam of light, at a specific wavelength or band of wavelengths, onto a semi-solid light-curable compound to cure the compound. The compound includes light sensitive, chemical components therein which, when exposed to the light at the specific wavelength, generally polymerize to harden the compound onto the work surface to bond, fill, or coat the surface.
As noted, such light-curable compounds are widely used in dental procedures. Dentists use light-curable compounds for tooth repairs in a variety of applications including a base, a liner, a coating, a surface seal, a filling for caries and cavities, and to secure crowns or similar dental structures to a tooth surface. Generally, visible light in a somewhat narrow wavelength band, such as the blue range of the light spectrum, will be sufficient to cure most commonly used dental compounds. Once cured, the dental compound functions, for example, to reduce further tooth decay, to bond dental structures, and/or to provide additional structural support to a tooth.
Generally, curing is effected by various instruments or devices capable of generating visible light, particularly a beam of blue light, and directing this light onto a tooth surface containing the light-curable compound. The blue light penetrates into the compound layer on the tooth surface for complete curing. The duration of the exposure to blue light for proper curing of the compound layer depends upon the light-curable compound itself, thickness of the compound layer, and the power and characteristics of the blue light emitted from the curing light instrument. For example, curing a compound to provide a thin tooth surface coating or veneer will require less light energy and a shorter curing time, while curing a compound to provide a thicker, deeper filling for gaps, such as caries and cavities, will require a greater amount of light energy and a longer curing time.
Presently, various prior art dental curing light devices utilized to deliver blue light to the tooth have exhibited various drawbacks. For example, the light directed towards the tooth inevitably exposes the surrounding oral tissue to certain wavelengths of light known to be undesirable for human tissue. Hence, curing light devices must be tuned to emit light at the proper wavelength to cure a specific wavelength sensitive light-curable compound for proper curing and have their output radiation limited to within a suitable wavelength band.
In one popular prior art curing light, a light bulb emitting a large wavelength band must be filtered to yield the desired narrow band of light. For example, a halogen bulb is used as a source of light intensity, raw visible light. Filtering of unwanted wavelengths of the visible light is accomplished by use of complex filtering devices or special filters, which receive broad spectrum light from the lamp element, and allow only the light at the desired blue wavelength to pass through or reflect onto the light-curable compound. The undesired wavelengths are then deflected back into the housing of the instrument. In addition to the high heat of the halogen bulb, such filtering also adds to the accumulation of heat during operation of the instrument. The heat must be dissipated for proper device operation and therefore, large heat sinks, fans and other devices are necessary to remove or re-direct the generated heat. Furthermore, the heat degrades the operation of the bulb and shortens its effective life.
Attempts in the art have been made to address such drawbacks of bulb-based curing lights, and several products exist which utilize solid-state light-emitting devices, such as LEDs, to generate narrow spectrum blue light that is suitable for curing light-curable compounds. Such devices do not require filters and operate generally cooler than a halogen bulb. They still are subject to heat considerations. For example, when used for longer curing times, they may tend to overheat. However, if the power to the LED chip or chips is increased to provide higher output and thus reduce the curing time, there is a greater concern about damage to the LED chip.
For example, the greater the light output of an LED component or chip, the higher its internal temperature. The manufacturer of LED-based curing lights must therefore address the internal heat generation of the LED element. If the internal heat is not controlled, it will cause irreversible damage to the LED element and its internal layers and electrical connections within, thus resulting in a permanently nonfunctioning curing device. Generally, LED chip manufacturers provide recommended power limits to minimize internal heat production. However, to provide even higher output levels for reduced curing times, curing light manufacturers may be required to “drive” the LED elements beyond the recommended levels. This further increases the possibility of a “meltdown” unless very technical, costly and efficient methods are utilized in the curing device.
Thus there is currently a tradeoff in trying to reduce cure times and boost light output while managing the heat generation aspects of an LED light engine. As noted above, larger, more complicated heat dissipation systems are not desirable, and particularly may not be appropriate for an LED curing device as such devices tend to be smaller and more compact anyway, as compared to a bulb-based curing device.
An additional concern with internal element heat generation and higher light output, dental tissue temperature is also a concern. Therefore, curing light devices must provide maximal composite conversion in less time while minimizing the potential for increasing tooth temperature and its possible iatrogenic consequences.
Thus, various curing light instruments of the prior art, with or without bulbs and filtering devices, are inefficient by virtue of the emitted light available to cure the compound and their heat dissipation. As a result, these instruments require more power output from the light source, increased light emission, and/or longer curing times. Consequently, such instruments also require larger and more efficient heat dissipation components that increase their overall cost and size.
Thus, there is a need to provide a curing light instrument to cure compounds in a fast, efficient, and effective manner, while improving convenience and reducing size and overall costs.
Accordingly, it is further desirable to provide a curing light instrument which efficiently and effectively cures light-curable compounds in reduced time by maximizing the amount of light directed onto the light-curable compound while controlling the amount of heat that is internally generated in the light engine and must be dissipated.
It is also desirable to provide such curing while reducing tissue temperature at the tooth.
It is also desirable to provide a curing light instrument that is small, portable and convenient to use for curing light-curable compounds.
It is further desirable to provide a curing light instrument requiring low maintenance and radiating light from energy efficient light emitting elements having a long life.
These and other objectives are met by the present invention.